Barack Obama has expanded his call for stricter control of the US financial sector into an across-the-board attack on the laissez-faire economics championed by Ronald Reagan, pursued by President George Bush for the past eight years, and embraced by the Republican candidate for the White House, John McCain.

The Democratic presidential candidate said he was not blaming Mr McCain in person for "the most serious financial crisis since the Great Depression" , but "the economic philosophy he subscribes to," based on tax cuts for the wealthy and the habit of "ignoring economic problems until they spiralled into crises".

During the Bush years, that philosophy insisted that "even commonsense regulations are unneccessary and unwise", with the result that the administration had sat on its hands as problems turned into crises – the latest being the convulsions on Wall Street.

Whatever its ultimate consequences, the crisis now shaking Wall Street seems bound to lead to greater federal government regulation of the financial sector, whoever wins the presidency in November.

And while the political fallout of the turmoil was not immediately clear, the more painful the effects of the upheavals on the wider economy the greater the impact will be on the election campaigns.

On past precedent, the crisis should work to the advantage of the Democrats, as the party out of power and thus not "responsible" for the crisis – and as the party with the reputation of having the economic interests of ordinary Americans at heart, rather than a favoured few.

However, as much as Mr McCain's handlers like to project him as an anti-establishment rebel, the Republicans have always been seen as the party of corporate America and of Wall Street, for whose current plight public sympathy is zero. With both campaigns now under pressure to produce detailed plans to tackle the crisis, the Arizona senator's admission that economic matters were not his strong suit may also come back to haunt him.

Even before the demise of Lehman Brothers, both candidates had come out against a federal bailout for the stricken investment bank, arguing the notion of "moral hazard" must be returned to financial markets.

But trapped between his support of most of Mr Bush's policies, including the $1.6 trillion of tax cuts, and his need to distance himself from a desperately unpopular administration, Mr McCain confined his fire to the excesses of the banks and investment houses, leaving the sharper attack to his Democrat rival.

The Lehman bankruptcy, Mr McCain said, was but "the latest reminder of ineffective regulation and management" that plagued the financial sector. A McCain-Palin White House would replace the "outdated and ineffective patchwork quilt of regulatory oversight in Washington" and bring "transparency and accountability to Wall Street".

That certainly is what Americans want. Well before the Wall Street debacle, polls showed the political pendulum shifting leftward, and away from Mr Reagan's famous crack about how the nine most terrifying words in the English language were, "I'm from the government and I'm here to help".

At the time, the president venerated by Republicans more than any other, caught the mood of the country – so much so that even Bill Clinton, the last Democrat to occupy the White House, declared that "the age of Big Government is over".

Now however, with inflation eating into pay packets, jobs disappearing and recession at the door, the notion of government that helps is back – and as the party identified with activist government, the Democrats and Mr Obama should be the beneficiaries.

Indeed, events have forced even the anti-regulatory and anti-interventionist Bush administration to change tack, with a $150bn (£84bn) stimulus package earlier this year to boost the economy, and assistance for some of the millions of Americans facing the loss of their homes to foreclosure. The scope of the measures has been criticised, but the change of direction is indisputable. The Obama campaign yesterday ridiculed John McCain's prescriptions for the economic crisis as "disturbingly out of touch" after he remarked during a campaign stop in Florida that he believed the economic "fundamentals" were sound, but promising he would "never put America in this position again".

A Democratic spokes-man replied: "Even as his own ads try to convince him that the economy is in crisis, apparently his 26 years in Washington have left him incapable of understanding that the policies he supports have created a historic economic crisis".

But the crisis could also help Mr McCain – even as its focus moves back to Wall Street. Mr McCain's post-convention "bounce" has given him a lift on economic issues too. In the summer, Mr Obama led by 15 points when voters were asked who they trusted best to handle the economy. Today, with the two candidates level in the polls, that advantage has shrunk to five points or less.

If the economic turmoil worsens, Mr McCain's strongest selling point, his battle-testedness under fire, may help. Voters could decide Mr Obama is too inexperienced to take office at a time of economic peril.